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In an A.C. circuit, a resistance of R ohm is connected in series with an inductor of self-inductance L. If the phase angle between voltage and current is 45°, the value of the inductive reactance (X_L) will be equal to ______.

Asked in GUJCET 2008 · Impedance and phase angle

Answer: (3) R

Step-by-step solution

Given: series L-R circuit with phase angle φ = 45°.

Idea: from the impedance triangle, the voltage leads the current by φ with tan φ = (X_L)/R.

tan 45° = 1, so (X_L)/R = 1.

Hence X_L = R: the reactance equals the resistance.

Why the other options are wrong

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